ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-3-447-2003On the use of mass-conserving wind fields in chemistry-transport modelsBregmanB.1SegersA.1KrolM.2MeijerE.1van VelthovenP.11Royal Netherlands Meteorological Institute, P.O. Box 201, 3730 AE, De Bilt, The Netherlands2Institute for Marine and Atmospheric Research Utrecht, Princetonplein 5, 3584 CC, The Netherlands1504200332447457This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article is available from http://www.atmos-chem-phys.net/3/447/2003/acp-3-447-2003.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/3/447/2003/acp-3-447-2003.pdf

A new method has been developed that provides mass-conserving wind fields for
global chemistry-transport models. In previous global Eulerian modeling studies a mass-imbalance was found between the model mass transport and the
surface pressure tendencies. Several methods have been suggested to correct
for this imbalance, but so far no satisfactory solution has been found. Our
new method solves these problems by using the wind fields in a spherical harmonical form (divergence and vorticity) by mimicing the physics of the
weather forecast model as closely as possible. A 3-D chemistry-transport model
was used to show that the calculated ozone fields with the new processing method agree remarkably better with ozone observations in the upper
troposphere and lower stratosphere. In addition, the calculated age of air in
the lower stratosphere show better agreement with observations, although the
air remains still too young in the extra-tropical stratosphere.